Radial Growth Patterns of Tree Species in Relation t Environmental Factors
|Title||Radial Growth Patterns of Tree Species in Relation t Environmental Factors|
|Year of Publication||1988|
To develop a more sensitive model of tree diameter growth, this study compared time series of annual ring increments with a selection of measured and derived environmental variables. The more commonly used monthly climatic variables (e.g., temperature, precipitation) do not adequately explain the year-to-year variations in tree growth, especially in view of current interests in partitioning the role of atmospheric pollutants in reducing tree growth in the northeastern U.S. Daily mean temperature and predicted daily soil moisture content for the last 29 years were used as the basis for the environmental variables used to “explain” the growth of four species of northern hardwoods: white ash (Fraxinus americana L.), American beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britton). Daily soil moisture content was estimated using the BROOK hydrologic model as calibrated by a subset of actual measured soil moisture data for the Hubbard Brook Experimental Forest. The general patterns of tree growth were analyzed and annual growth of each species was evaluated by applying an autoregression model (lag 1) to linearly detrended index series derived from the ring-increment measurements. After changing patterns of the environmental factors were described, new variables were quantified on the basis of a newly proposed tree growth period. The relationships between tree growth fluctuation and the environmental factors were analyzed by applying the correlation analysis, simple linear regression analysis, factor analysis, and principal component analysis. Generally, the species showed diverse growth responses under similar environmental conditions and some stress related variables significantly explained tree growth fluctuation either positively or negatively. In addition, environmental conditions of late summer of the previous year were important in determining tree growth of the current year. Highly variable soil moisture regime seems to be more responsible for the diversity in growth responses of the species than temperature regime. The multivariate analysis permitted a description of the environmental responses of the four tree species, thus aiding a comparative analysis of how ecological niches of the trees differ. Use of biologically relevant environmental variables in dendroecological studies should both permit a better understanding of natural controls on tree growth, and also increase the sensitivity of our current techniques to evaluate anthropogenic stress in natural ecosystems.